The standard dosage for oral Benadryl is 1 mg per pound of body weight, given 2-3 times a day. Most drug store diphenhydramine tablets are 25 mg, which is the size used for a 25 pound dog. read more
Generally the occurrence of side effects in dogs given Benadryl is very low. Too high of a dose may result in increased sedation. If any strange side effects are noticed in your dog after they are given Benadryl they should be taken to a vet to be properly examined. read more